This invention relates to integrated circuits and, more particularly, to a read-only-memory (ROM) unit fabricated in large-scale-integrated (LSI) form.
Read-only memories are well-known units that constitute one of the basic building blocks useful in assembling a variety of practical electronic systems such as microprocessors, telephone PBXs and electronic key systems. In recent years, considerable effort has been directed at fabricating such systems, including the ROM units thereof, in LSI form. In fact much of this effort has been concerned with designing improved ROM units.